Homogeneous body of highly-refractory metals.



'NNLTE STATES PATENT fFRrOE.

WERNER vON BOLTON, or OHARLOTTENRURG, GERMANY, ASSIGNOR vTo y SIEMENS a HALSKE AKTIENGESELLSCHAFT, or RERLIN,l GERMANY.

HOMOGENEOUS BODY OF'HIGHLY-REFRACTORY METAL-s.

Specification of Letters Patent.

Patented April lio, 1906.

Original application filed January 1904, Serial NO- 187,830. Divided and this appllcaioniled September 29,1905. SeralNo; 280.639.

To all whom t may concern,.-

Be it known that I, WERNER voN BOLTON,

a subject oi' the German Emperor, residing at Charlottenburg, near Berlin, Germany, have made a new and useful Invention in Homogeneous Bodies of Highly-Refractory Metals, of which the following is a specification.

My invention is directed particularly to a homogeneous body of highly-refractorymetal, such as tantalum, which has a fusing-point at above 2,000O Celsius; and it has for its object to provide a metal of this nature which shall be ductile or capable of being rolled into thin sheets or rolled or drawn into wires or rods.

Prior to my invention, so far as I am aware, there did not exist a relatively pure metal of a highly-refractory type, such as tantalum, which was ductile or capable oi being rolled or drawn, and such a product being newwith me constitutes the essence of my improvement. What has been hitherto known in the art as tanta/lum, which occurs in the form ot oxids or carbids of the metal, is an impure amorphous powder not homogeneous and not ductile. Pure tantalum does not exist in nature in the state'of a homogeneous ductile body. In fact, tantalum metal, as such, does not exist in the natural ustate at all. It exists only in the condition of orescontain-4 m vtantalurnV-such, as, for instance, in thel co umbite ore. Up to the present time it hasbeen possible to extract from this ore an amorphous gray powder ,of tantalum only, or a more or less coherent m'ass of impure tantalum which did not form inany way a homogeneous body and which was absolutely inductile. These tantalum compounds, were useless for technical purposes.

I have discovered thatby suitably treating the amorphous powders or tantalum compoundsin the way, for example, as described in my prior application, Serial N o. 187,830, iiled in' the United States PatentOilice,J anuary 5, 1904, of which the present application is a division, there may be produced a homogeneous ductile body highly refractory which has amelting-,point at above 2,000D Celsius. This new metal I call substantially pure metallic tantalum, and it is distinguished from the impure products formerly known as tantalum,' as above indicated by possessing the qualities of ductility and nomogeneousness, while the impure compounds are v 1 it together or to give toit acoherent or relatively solid mass and then'pass a current of.

electricity through it, preferably While itis submerged in a rare atmosphere approximatin a vacuum. For best effecting this the m ss of compressed powder is'secured between clamps of tantalum constituting the terminals ofa source of electrical energy.

nest point, or at the point of smallest crosssection, and hence highest resistance. An arc is therefore formed at the fusing-point,

and in vthis arc the further partsof the bar melt down, so that more or lesslarge beads of "molten metal collect at the molten ends.

These beads drop off as, the fusing proceeds.

The small bars of compressed metal powder are placed on a plate of very refractory metal-for instance, of tantalum which forms one electrode-the ot er electrode being then approached to this bo y of compressed metal powder until both come into contact with each other. Thereupon the other electrode is somewhat removed again, whereby an arc is formed in which the body of metal powder gradually melts. The molten body remains on the plate. It is also possible, of course, to place a Crucible below the arc and allow the molten metal to go on'dropping into it as the usin proceeds.

If tte molten metal is brought into contact during the fusing process 'with other substances with which it is very liable to combine chemically at high temperatures, the rosult will be a strongly impure product and as almost all very refractory metals arc most apt to chemically combine with other Substances at the high temperatures here 1n question, it is Vextremely dillicult to obtain a pure metal. Above all, no carbon must be used as an electrode for fusing the metal, as

' 'The metal commences to fuse as soon as an IOO otherwise the metal would take up too much carbon and might under circumstances be changed into a carbid. Furthefr, all oxygen must be kept away, and therefore all air must be pumped out of the fusing vessel 'as far. as possible. Tantalum metal and many others are also liable to chemically combine with nitrogen', hydrogen, &c., and consequently these injurious gases must also be kept away. Therefore I prefer to execute the fusing process in a vacuum as perfect as can be obtained and to vhave the electrodes between which the fusing takes place out of the same metal as that which is to be fused.

I have found that it is best to use direct current for thev fusing process'and to bring the metal to be fused into contact with the positive electro'de. This electrode may consist, for instance, of a small plate of the same metal as that which is to be fused. AThe negative electrode may consist of another metal,

as it will not so easily be brought to fusing.

4The metallic body formed according to this process is quite homogeneous and has a very high `degree of ductility. Thus it is possible without difficulty to produce quite homogeneous bodies of tantalum metal. raw material is used for the purpose and if all impurities are kept away during that fusing process, the tantalum metal so obtained will vhave such a high degree of ductility that it -can be rolled into very fine sheets and drawn into the finest of Wires7 while formerly it was generally thought that pure tantalum metal was quite brittle and could in no way be worked mechanically.

If purev It will be apparent that the new metal having the characteristics described vwill have a wide use inthe arts Y I make no claim hereinafter to the method or process hereinbefore described, as this constitutes the subject-matter of the before-mentioned original application, my claims in the present instance being directed generically to the product which results from such process,

vthere not having been known in the art of pounds and possessing the qualityrof being homogeneous and ductile.

`2. Substantially pure metallic tantalum possessing the qualifications of homogeneous- `ness and ductility.

'In testimony whereof I have signed my name to this specification in the presence of two vsu bscribing witnesses.

WERNER VON BOLTON.

Witnesses: i 1

HENRY HASPER, WOLDEMAR HAUPT. 

